Vehicle transmissions conventionally have a plurality of synchronizers. The synchronizers transfer the torque from various shafts to the gears and from gears to shafts through splines. It is important to connect the synchronizers to the shafts in such a way to prevent axial movement of the hub of the synchronizer relative to the shaft. One common method for attaching the hub of the synchronizer to the shaft is to press fit the hub on to the shaft. Unfortunately, the press fit varies due to manufacturing tolerances. Thus, gear loading through the hub of the synchronizer to the ground or structural members (i.e. transmission case walls, center supports, etc.) can unseat the synchronizer hubs and cause them to move axially. Eventually, axial movement of the synchronizer hubs will increase the clearance between the shaft and the hub splines, which will lead to high operating noise, and may cause shaft and/or Hub failure.
Known prior art solutions use additional features (i.e. additional snap rings or bearings pushed on shafts with a heavy press fit) to secure the synchronizer hubs to the shafts. While these methods may improve the connection of the hubs to the shafts these prior art methods do not eliminate axial movement of the synchronizer hubs. For example, the clearance between the snap ring and bearing race or gear hub, which allows the synchronizer hub to move axially and eventually may cause the synchronizer hub failure.
While shaft bearings (i.e. tapered bearings) reduce axial movement of the synchronizer hubs in the early operating life of the transmission, axial clearance which causes axial movement of the synchronizer hub is not eliminated. Moreover, over time the bearing races move axially due to a creaping process and, consequently, allow the synchronizer hub to move axially and in turn may lead to synchronizer hub failure.
Accordingly, a new and improved apparatus and method for retaining the synchronizers and other components on a transmission shaft is needed.